Stoker apparatus



Jan. 5, 1954 D. l.. GE-rz x-:T AL 2,665,071

STOKER APPARATUS Filed Nov. 14, 1949 4 Sheets-Sheetll Fl-l lullll 65 6770 mmm- @M 3.9%

ATTORN EYS Jan. 5, 1954 D. l.. GETz ET AL 2,665,071

STOKER APPARATUS Filed Nov. 14, 1949 4 Sheets-Sheet 2 L g8 .85 s 82 C/l' a 6 8 7L mmm@ ATTOR N EYS Jan. 5, 1954 D. L. GETZ ET AL STOKERAPPARATUS Filed NOV. 14, 1949 4 Sheets-Sheet 5 I8 1E 8O I 18 17 m v l/f;

ATTORNEYS Jan. 5, 1954 D. 1 GETZ ET Al.

STOKER APPARATUS 4 Sheets-Sheet 4 Filed Nov. 14, 1949 ATTORNEYS PatentedJan. 5, 1954 attach STOKER APPARATUS Delmond L. Getz and Edward C.Lafferty, Springeld, Ohio, assignors to The Steel Products EngineeringCompany, Springfield, Ohio, a corporation of Ohio Application November14, 1949, Serial No. 126,962

8 Claims.

This invention relates to stokers and more particularly to a modulatingtype stoker system.

In the ordinary installation of a stoker, particularly the type employedin household heating plants and the like, it is customary to employ athermostat or other heat sensitive element which controls the operationof the stoker so that it is either on, when the temperature to becontrolled is below the desired value, or off when the temperature isabove such value. While such controls are satisfactory from thestandpoint of maintaining desired temperature conditions, it has beenfound that such a system is open to objection from the standpoint ofsmoking conditions, the smoking usually occurring upon the shutting downof the supply of fuel, because there is a concurrent stoppage in thesupply of combustion air from the blower, such sudden shutoff frequentlyproducing smoking.

In accordance with the present invention a heat sensitive controlis'provided which maybe actuated either by the temperature in the spaceto be controlled, or by the pressure, as in a boiler forexample, andwhich is of such character that it has a range of positions, varyingfrom a high to a low demand for heat, as distinguished from a mere onand off position. This modulating control element is then associatedwith a stoker system incorporating a fuel and an air supp-ly means insuch manner that both the rate of supply of fuel and of the air areVaried or modulated in accordance with the position of the heatsensitive control. Thus under cold weather conditions where a high rateof heat supply is necessary, the system produces a rate of operation ofthe fuel supply means which is correspondingly high. This is accompaniedby a proportionate increase in the rate of introduction of combustionair. A's the demand for heat becomes less, the control modulates theaction of the supply system, reducing, but without terminating, the rateof introduction of fuel and thereby maintaining a desired temperaturecondition with such lesser heat input. Concurrently the supply of air isreduced to the proper level corresponding with the reduced rate of fuelsupply.

Normally this modulating control continues to function, the thermostator heat responsive element providing for either increasing or decreasingthe correlated rates of fuel and air supply, but without actuallyterminating such supplies, and hence effectively producing oreliminating the smoke condition referred to above and providing improvedoverall combustion, maintaining a more uniform depth of fuel bed, andresulting in higher overall efficiency.

The stoker system preferably employedis one which operates on anintermittent basis, and this in turn is controlled by a cyclic timecontrol member with the fuel being supplied intermittently for a greateror lesser part of each cycle of the device. Thus when the demand forheat is the greatest, the control may produce such feeding operation ofthe fuel substantially throughout the entire portion of the cycle; asthe demand for heat decreases, the portion of the cycle during which thefuel supply continues is progressively reduced to a minimum, whichminimum however is sufficient to keep the furnace in operation on astandby basis, thus assuring that it will be ready and in condition fora higher rate of operation whenever desired and without the completeshut down of fuel and air supply which had led to the undesirableconditions described above.

There is also preferably provided a manual controlwhich can be used tooverride the automatic action of the system and to provide forterminatingthe fuel supply while continuing the flow of combustion air,when for example it is desired to allow all of the fuel in the furnaceto burn out, either for shutting down the furnace, or for the necessaryremoval of clnkers, or the like.

It is accordingly the object of this invention to provide such a stokersystem which is responsive to a heat condition to be maintained andwhich modulates the supply of fuel and air in correlated relation toeach other and in accordance with the requirements for heat, whilemaintaining a continuity of operation and avoiding the objectionablesmoking and other conditions associated with an abrupt and completestopping of the operation.

Other objects and advantages will be apparent from the followingdescription, the accompanying drawings and the appended claims.

Referring to the drawings- Fig. l is a view in elevation with certainparts being broken away showing a stoker constructed in accordance withthe present invention;

Fig. 2 is a view of the stoker at right angles to the showing in Fig. 1;

Fig. 3 isa detail view partly in section showing the damper control forregulating thesupply of air;

Fig. e is a schematic layout in perspective showing the drive andcontrol system in accordance with the present invention;

5 is a view in vertical section through the gear casing of the device onthe line 5-5 of iig'. 6 Vwith parts shown in elevation;

Figs. 6, 7 and 8 are vertical sectional views on the lines i-, 'i-l andS--S of Fig, 5,1espectively;

3 Figs. 9, 10 and 11 are sectional views on the lines 9-S, El-I andIi-II of Fig. 8, re-

spectively 12 is a view on an enlarged scale through the drive shaft ofthe stoker showing details of the control mechanism; and

13 is a vertical detail sectional View through the manual control forpositively terminating the operation of the Stoker.

Referring to the drawings which disclose a preferred embodiment of theinvention, the stoker is shown by way of illustration as having a maindrive motor I serving as a source of power, which is enclosed within acasing II mounted upon the main gear casing I2. The motor has a drivepulley I 4 which carries V-belts i that drive pulley I6 on the maindriven shaft I'! suitably journaled in casing l2 on antifrictionbearings I 8. The shaft i1 extends through the gear casing and on itsopposite end is directly connected to the rotor of a sirocco type blowerwhich operates in blower housing 22. The blower inlet is shown at 23 andis provided with a series of vanes 25 which are mounted for rotation onindividual shafts 25 between relatively closed and open positions thuseffectively throttling the inlet to the blower and providing forregulating the amount of combustion air.

The control responsive t0 the heat condition to be maintained is showndiagrammatically at S0 in Fig. fl and is of suitable type to provide thedesired modulating control, such as a Variable electrical current flow,depending upon the heat condition to be maintained. Such control iselectrically connected as shown at 3! to an actuator 32 which issupplied with low voltage current by transformer 33 from power lines 34.The actuator is arranged so that its control shaft S5 rotates and thusrocks the sector 36 from one angular position to another, correspondingto the operation of control 30. In the arrangement illustrated in Fig.4, the sector 36 is arranged to rotate in a clockwise direction inresponse to an increasing demand for heat. A suitable modulating controli and actuator 3| for use in the present system is aMinneapolis-Honeywell L-91 control with M904E Modutrol motor.

Connections are made from this actuator 32 to regulate both the airsupply and the fuel supply an-d such supplies are varied in correlatedreation with each other. Referring first to the mechanism for regulatingthe supply of air, a rod iii is connected to a suitable point on sector36 and at its opposite end to the lever 42, a series of apertures beingformed in the lever in which the .fr

rod may be selectively positioned to secure a different amount ofmovement, depending upon the particular adjustment desired. Lever 42 isfixed to a pivot pin d4 rotatably supported in the wall of the gearcasing I2.

A second rod is also connected to lever 42 and at its upper end ispivotally connected to a crank 5i secured to shaft 52 rotatably mountedin bracket 53 which in turn is supported from the gear casing. Theopposite end of shaft 52 is connected with a link 55 and this in turnoperates through a link 55 to rotate crank 51 secured to shaft 58rotatably supported in brackets 59. The opposite end of the shaft 58carries a crank 5U connected to a link 5I which carries a lever 62 atits opposite end, lever G2 being connected to the shaft 25 of the damperin such manner that upon adjustment thereof, the damper will be causedto oscillate on the axis of shaft 2S between its open and closedpositions.` It will thusr be evident that in response to operation ofthe actuating sector 3S, there will be a direct and correspondingadjustment in the setting of the damper, providing for opening thedamper with increasing demand for heat and thus correlating the rate ofair supply with the rate of fuel supply. It will be understood that thevarious linkages may be so adjusted as to obtain the precise movementsof the damper for each setting of the actuator as desired to give aspecific volume of air flow determined to be correct for that rate offuel consumption.

The fuel is supplied to the combustion Zone by means of a suitableconveyor, and for purposes of illustration the invention will bedescribed with reference to a stoker arrangement adapted to withdrawsolid fuel from a bin and feed it into a retort, such as the arrangementshown in Scholl Patent No. 2,364,166, assigned to the same assignee asthis application. In suoli a system one fuel conveyor tube such as 55provides for withdrawing fuel from the bin, under the action of aninternal worm conveyor indicated at GG, the fuel being transferred in atransfer chamber G' to a second fuel conveyor tube 68 having a similarconveyor worm 69 therein for feeding the fuel forwardly to the retort.The drive shafts of both conveyor worms 65 and 5S extend beyond the wallof the chamber *31 and on their overhanging ends carry drive sprocketsl0. Chains II connect each sprocket I0 to driving sprockets 'I-l and areprotected by covers I3, such driving sprockets being mounted uponopposite ends of the drive shaft "M, suitably journaled in the gearcasing. Thus upon the rotation of such shaft 'I a corresponding andidentical rotation of the two conveyor nights is produced, withconsequent supply of the fuel from the bin, or other reservoir or fuelsupply chamber as the case may be, forwardly and into the retort.

In order to provide for the desired intermittent but controlledoperation of shaft i4 and the corresponding operation of the worms tosupply the solid fuel, the mechanism in gear case i2 is provided asfollows. Shaft I'I carries a worm 89 which drives the worm gear 82loosely mounted on shaft 14. The gear has a laterally extending hub 82awhich is pinned as shown at 83 to the hub 84 of a cam 85, the camtherefore rotating freely on shaft le, being directly driven from gear82.

A follower in the form of a roller (il rides against the surface of cam85 and is rotatably supported by a pair of rocker arms 8S suitablymounted on pivot shaft B journaled in the gear casing I2 by suitableantifriction bearings 9| (Fig. 9).

Shaft has an additional arm 93 extending radially therefrom and a crosspin 94 extends from the two arms 8S to arm furnishing a support for theconnecting links 85 which are carried on pin 84 and held in properspaced relation thereon by means of Cotter pins 96. A projecting pin 9iextends from the lower end of arm 93 and is formed to receive tensionspring 98 which normally acts to swing shaft 95 about its axis and thusto maintain roller 8l in continuous riding contact against the surfaceof cam 85.

Connecting links 95 extend upwardly to a main feed pawl I which isrotatably mounted upon pivot pin II which in turn is carried by a pairof radius plates |62 loosely mounted on the hub of a main drive ratchetwheel IDE. The pawl is in such position that when it is moved in acounterclockwise direction (Figs. 7, 8 and 12) under the cammingactionof the rockerarrn assembly, it will drive the ratchet 'wheel |05also in'a'counterclockwise direction. The ratchet `wheel has Aanextended hub |86 through which `there extends a shear pin |07 forming arupturable driving'connection with `shaft M. Thus rotation of theratchet `wheel |65 `effects corresponding direct driving movement ofvshaft M up tothe 'limiting strength of 'the `shear pin which isincluded for safety purposes. As'shown in Fig. 5 'the'shaft 'M isVdirectly journaled at one `end in antifriction bearing `|03carried'bycasing '52, and at Vits other end is supported. inslecve whichin turn is gournaled in antifriction rbearing 'id carried by the casing.A retaining :pawl H19 pivotally mounted on pin I in the casing -I2 vandnormally urged Itoward engaging position by weighted end |12 serves vtoprevent backward rotation of ratche'twheel |05.

Atiming ratchet wheel i |1'5is mounted for -free Arotation on the hub|05 of the main ratchet |55 and `is arranged to be driven by a pawl H5carried on the pin ||l`| fand hence movable lin corre sponding timedrelation with the rocker arm 83 under the driving `action of the eain135. retaining pawl is mounted on and al'A ranged opposite the teeth ofpawl i |5 to prevent backward rotation thereof, such pawl being suitablyweighted as shown at llt to bias it toward engaging position. Timingratchet wheel H5 may thus operate independently of the main ratchet |d5,and is formed with an axially ezitending hub portion which is shaped asshown in Fig. B to define a series of cam steps |21A Preferably thesesteps progress from a minimum to a maximum and back to theminimum'position in a continuous series of relatively small increments.

A cam follower inthe form of ka roller |25 (Figs. 4 and 12) is arrangedto `ride the cam surface |2|, the roller being carried by a rocker arm|26 supported on the positioning lever |21 by means of pin |23. Lever|2`| is secured to the pin 44 and oscillates with such pin, therebyswinging the roller |25 closer to or farther away from the surface ofcam |2 l. Rocker arm |26 is connected through a floating pivot with alink |3| and through it with operating lever |32. Lever |32 is securedto and causes rotation of a, 'sleeve |33 suitably journaled in a portionof casing l2 (Fig. 13). The sleeve is normally biased by means of atorsion spring |35 acting against sto-p pin '|36 in the direction tocause the lever |32 to swing in a counterclockwise direction as shown inFig. l2. A shaft |31 extends through sleeve |33 and its inner endprovides a pivot for loosely receiving an interference arm |33 whichprojects radially therefrom and toward and under a laterally projectingtongue |39 on the main drive pawl |00.

Sleeve |33 has a projecting finger |40 fixed thereto which is arrangedto engage pin |4| carried by interference arm |38 so that upon rotation`of sleeve |33, the interference arm will be raised to lift pawl Ill outof driving engagement with ratchet wheel |85, or lowered to establishand render such drive operable. A second finger |42 is likewise formedon sleeve |33 in `position to receive the pin lill when the interferencearm is swung away to a clearance position, preventy ing excessive travelthereof.

When the interference arm |38 is in position to raise the main drivepawl, causing it to rock about its pivot shaft Il, such pawl is retainedin the clearance position in which, notwithstanding the rockingVmovement of `the Vrocker arm and-of 'the radius plates |2, it no longerhas driving engagement vwith the teeth of the main drive ratchet |65.This prevents the transmissionof any driving power to the worm drive`shaft 14 as long as this condition exists. However in response to thelowering of the interference arm, the main drive pawl lill] is thenallowed to engage the teeth of the drive ratchet |05, providing forestablishing the driving connection to the worm drive shaft 1d.

The operation of the system takes place as follows. lWith the drivemotor in operation, shaft is driven at a continuous and substantiallyconstant rate of speed, and this in turn produces rotation of the mainworm gear 82 and of cam 85. In response to rotation of cam 85, rockerarm 88 oscillatcs about its pivot shaft 90, and this in turn through theaction of the connecting links produces a corresponding oscillatorymovement of the radius plates l? and the pawl assemblies carriedthereby. This includes the main drive pawl lill and the timing cam pawlIIB. Since there is no interference at any time with the driving actionof pawl H6, such oscillatory movement produces a corresponding step by'step advance in the rotation of the timing ratchet l5, and a similar orstep-by-step movement of the timing cam 2| Under the action of thebiasing spring |35 the sleeve |33 and its supporting nger |55 tend to beshifted in a. counterclockwise direction as shown in Fig. l2, with theresult that the finger I 40 picks up the pin IM, and causes interferencearm |38 to be lifted, thereby engaging the projection L|351 on pawl |90,raising it to and retaining it in its inoperative position. Thisinterrupts or disables the drive to the worin operatlng shaft lll, butdoes not interfere with the cont1nuous step by step rotation of thetiming cam. As the timing cam rotates, at some point in its rotation itwill engage the roller |25, causing that roller to rise, thus rockinglever |25 about pivot |28, which in turn causes the motion to betransrn1tted through link |3| and lever |32, rocking lever |32 inaclockwise direction and thus overcoming the biasing action of spring|35. Such rotation of the sleeve results in the lowering of finger |49and of interference arm |38, thus allowing the main drive pawl it todrop int@ driving relationship with the teeth ofn the main ratchet wheel|05, As long therefore as the cam engages roller |25, and thus retainsthe interference arm in withdrawn position, each successlve step ofmovement of the rocker arm SS will cause a corresponding drivingengagement of the pawl with the ratchet IE5, producing a correspondingstep of rotary movement in shaft 1li.

Y The particular point in the cycle of the timing cam at which theroller is engaged is determined by the setting of lever |27, and this inturn is controlled through operation of lever d2 and the positionmgofthe sector 3G of the actuator. As the 'actuator changes its positionin response to Vthe demand for heat, lever |27 is rotatably Vaddusted'and'this produces a corresponding shiftmgm the 'position of roller |25,causing it te be engaged either earlier and thus for a greaterportion'of the cycle, or later and thus for a lesser portion of thecycle of rotation of the timing cam. In .this way the number of strokesof advance movement of the worm drive shaft n'Ul `which occur duringeach Vtiming cvcle may be varied, va suitable `control providingtwenty-one positions on the cam and thus making it possible to vary therate 0f feed over a range varying from one step per revolution totwenty-one steps and hence substantially continuously throughout theoperation of the system.

As the rate of fuel supply varies under control of the modulatingcontrol, the actuator 32, working through connections 4S, 42, 5S and therelated linkage, provides for a corresponding adjustment in the settingof the vanes 25 and thus regulation of the supply of combustion air ismaintained in completely correlated relation with the supply of fuel.

In some cases it is desirable to provide for manual control of thestoker in order to be able to shut oif the sup-ply of fuel completelywhile allowing,r the motor drive to continue for the purpose ofsupplying combustion air and thus completing the combustion of the fuelalready in the retort. For this purpose the control illustrated in i3 isincorporated, and includes a manual control member ESQ in the form of alever which carries a yieldable detent l5| to yieldably retain the armin either the manual or automatic position. In the automatic position,the operation takes place in the manner already described. However whenthe handle is adjusted to the manual or off position, the shaft |31 isrotated within sleeve E33 and in so doing a nger |52 thereon is causedto engage beneath pin Ml, causing the lifting of the interference arm toa continuing interference position. Thus regardless of the position ofroller I 25, which would otherwise lower the interference arm at somepoint in the timing cycle, the interference arm remains in its raisedposition, thus completely disabling the drive and preventing therotation of shaft 14. Meanwhile the drive motor continues to operate andthus the blower continues to supply combustion air, allowing completecombustion of such fuel as remains upon the retort.

It will thus be seen that the invention provides a simple and highlysatisfactory arrangement for continuous modulating control of the supplyof fuel, providing for the intermittent operation of the fuel supplyworms for a predetermined and variable portion of a timing cycle asrequired to bring about the proper rate of fuel supply. There is acorresponding operation and correlation of the rate of air supply fromthe blower so that proper modulated control of the air is likewisemaintained, in order to establish and maintain the most efficientcombustion conditions. The system thus assures the operation of theStoker at such a rate as to maintain a predetermined heat condition, andwith a continuously varying rate of supply to meet the demand. There isno abrupt change in operation such as an on and olf condition, and theobjectionable smoking and inefficient combustion associated with suchtype of operation are effectively avoided.

While the form of apparatus herein described constitutes a preferredembodiment of the invention, it is to be understood that the inventionis not limited to this precise form of apparatus, and that changes maybe made therein without departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

1. A stoker system operable to provide a variable rate of fuel supply ina selected number of uniform feeding strokes of a fuel feeding memberduring an interval and under control of a modulating device responsiveto a heat condition to be maintained, comprising a main drive ratchetconnected to said fuel feeding member for operation thereof, a maindrive pawl adapted for operating engagement with said main driveratchet, means for continuously oscillating said main drive pawl toproduce a series of uniform feeding strokes of said feeding member whensaid pawl is in engagement with said main drive ratchet, an interferencearm for retaining said main drive pawl out of driving engagement withsaid main drive ratchet, a timing cam rotatable separately from saidmain drive ratchet and having a series of steps thereon ranging from aminimum to a maximum in small increments, means operated by saidoscillatory means for producing uniform periodic advancing movements ofsaid timing cam in response to each said oscillatory movement, a camfollower, means actuated by said modulating control for adjusting saidfollower in predetermined position relative to said cam to be engaged bya portion of said steps in the course of the revolution thereof, andlinkage connecting said cam follower with said interference arm to causesaid interference arm to be withdrawn allowing said main drive pawl toengage said main drive ratchet during the period that said cam followeris raised by the steps of said cam.

2. A stoker system as defined in. claim l in which the timing cam isadvanced by a timing ratchet, and in which the means operated 'oy theoscillatory means for advancing the timing com includes an auxiliarypawl engaging timing ratchet.

3. A stecker system as defined in claim 2 in which the timing ratchetand the main drive ratchet are mounted coaxially with each other.

4. A stoker system as defined in claim 2 in which said main drive pawland said auxiliary pawl are carried on the same oscillating means.

5. A stoker system as defined in claim l in which the steps on thetiming cam are arranged in a series which increases and then decreasesthrough a uniform series of increments.

6. A stoker system as delined in claim. l in which the interference armis normally biased toward interfering position and is positivelywithdrawn in response to engagement of said cam follower with a step onsaid timing cam.

7. A stoker system as defined in claim l including means for regulatingthe air supply, and means operated by said modulating control for alsoactuating said air supply regulating means in coordinated relationtherewith.

8. A stoker System as dened in claim including a manual control forterminating the supply of fuel by said feeding member while continuingthe air supply.

DELMOND L. EDWARD C. LAFFERTY.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,335,008 Miner Mar. 3 i920 1,345,652 Tutein July '3, 19231,472,280 Ousdahl Oct. 3 0, 1923 1,520,922 Baker Dec. 3), 122A 2,145,942McAdams Feb. 7, i539 2,354,517 Hallinan July 25, 1944 2,393,680 HallinanJan. 29, 1946 FOREIGN PATENTS Number Country Date 592,993 Great BritainOct. 6, 191i?

